With development of the display technology, high resolution and low cost of the display product is the important development direction of the current display product. However, with increase of the resolution of the display product, an area occupied by each pixel on the display panel becomes smaller, so that a storage capacitor in the pixel circuit becomes smaller, and thus compensation characteristic of the pixel circuit is degraded. Likewise, in order to reduce production cost of the display product, the number of mask plates in the manufacturing process of the display panel might be reduced generally, i.e., the manufacturing process steps are simplified. The reduction of the mask plates, i.e., the simplification of patterning process steps, enables the storage capacitor in the pixel circuit to be made of a metal layer (i.e., a gate) and an active layer (i.e., a source-drain). In this case, medium thickness of the storage capacitor can be determined by means of the metal layer and the active layer, and is thus large. In this way, the storage capacitor in the pixel circuit may also be small, thereby resulting in a poor compensation characteristic of the pixel circuit.
Therefore, there is a requirement of improving the compensation characteristic of the pixel circuit.